2/22/2016 1 Natural Selection and adaptations “Observing Evolution In Action” Natural Selection Mimicry Camouflage Charles Darwin http://ed.ted.com/on/D0Ngvotw ► Darwin explored The Galapagos Islands from April through October 1835. Entire voyage of The Beagle : Dec 1831 - Oct 1836 ► When and where he started thinking about what was to become his theory of evolution by natural selection. ► He did not publish his thoughts until the publication of The Origin of Species in 1859. 2
Transcript
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Natural Selection and adaptations
“Observing Evolution In Action”
Natural Selection
Mimicry
Camouflage
Charles Darwinhttp://ed.ted.com/on/D0Ngvotw
►Darwin explored The Galapagos Islands from April through October 1835.
Entire voyage of The Beagle: Dec 1831 - Oct 1836
►When and where he started thinking about what was to become his theory of evolution by natural selection.
►He did not publish his thoughts until the publication of The Origin of Species in 1859.
► Biological evolution is change in species over a LONG period of time.
►This was not a new idea at the time
►But there were no good mechanisms to explain how these changes occurred
► Darwin concluded that evolution happens BY Natural selection
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The Galapagos Islands
► Located approximately 1000km from the coast of Ecuador, South America.
► This is just a little closer than the distance between Chicago and Philadelphia.
Mostly ground between the two U.S. cities.
Mostly deep water between the Galapagos Islands and the coast of South America.
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Galapagos Islands –located off the coast of Ecuador
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►The voyage of the Beagle
Figure 13.1B
North
America
Great
Britain Europe
Africa
Equator
Australia
Tasmania
New
Zealand
Cape of
Good Hope
South
America
Cape Horn
Tierra del Fuego
Galápagos
Islands
Pacific
Ocean
Atlantic
Ocean
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Endemic Species -Organism native to a certain location
► Among the kinds of animals
found here and nowhere else: 1 giant tortoise species
1 marine iguana species
Several species of birds such as finches
1 penguin species
7 species of lava lizard
14 species of sea cucumber
1 species of sea lion
1 species of hawk
several species each of mockingbirds, doves, owls, flycatchers, and yellow warblers
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The Finches
► Darwin’s main focus of study were the 13 finch species include: 6 species of ground finches
3 species of tree finches
1 woodpecker finch
1 vegetarian finch
1 mangrove finch
1 Coco Island finch
►A warbler finch that looks more like a warbler than a finch (one of the tree finches).
► The woodpecker finch actually uses cactus spines to dig grubs out of branches!
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Darwin’s Finches Speciation►Due to the distance
between the islands, the finches became isolated and no longer bred easily with finches on other islands, leading to distinct species, each with a unique beak size
►As a result, they became different species this is called Speciation
►Natural selection explains the mechanism of evolution – it is Darwin’s explanation of HOW organisms are able to change over time.
► “Survival of the Fittest”
► Examples:
Pesticide-resistant insects
Antibiotics-resistant bacteria
Figure 1.6B
(1) Population with varied inherited traits
(2) Elimination of individuals with certain traits
(3) Reproduction of survivors
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Natural Selection
►Is there any evidence of Natural Selectiontaking place in real populations?
►One study, performed during the industrial revolution in England, demonstrated that populations of organisms ARE greatly affected by environmental changes
The Peppered Moth
► Two different forms of the moth existed
► Dark and Light
► Both forms were common
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Natural Selection At Work
►What kind of tree would you expect the Dark moths to sleep on?
►What kind of tree would you expect the Light moths to sleep on?
Natural Selection At Work
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The Effect Of A Changing Environment
►What do you think might have happened to the trees that were near coal-burning factories and power stations? They became covered in black carbon soot
►What do you predict might then have happened to the moth populations in these areas? In heavily industrialized areas, the Light form of the
moth almost disappeared, because of predation
The Dark form became dominant in these areas because of Natural Selection
Antibiotic Resistance
►Because bacteria reproduce so quickly, they represent excellent specimens for testing Natural Selection
►Watch how quickly they can “evolve” because of Natural Selection…
►Results from reproductive isolation - when members of two ancestral populations can no longer interbreed to produce fertile offspring►How do populations get isolated?....
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►Behavioral Isolation
►Two populations are capable of breeding but have different
mating rituals
Eastern Meadowlark Western Meadowlark
Both birds are in the
same geographic range but
they have a different
mating song
Isolating Mechanisms
Isolating Mechanisms
►Geographic Isolation
►Two populations become separatedby geographic barriers like rivers,
and mountains
Abert squirrel Kaibab squirrel
Colorado river separated
this species into two
separate populations. A
new subspecies formed –
the Kaibab squirrel
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Isolating Mechanisms
►Temporal Isolation
►Individual varieties of an organism may breed at different
times of day/year
Ex. Orchids in a rainforest
Mass Extinctions
► Wipes out whole ecological systems
► More than 99% of all species that ever lived are now extinct 5 mass extinction
events in Earth’s history
► Burgess Shale (many extinct organisms that were VERY different from modern organisms)
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• 1. There is competition for limited resources
• 2. There is natural variation(behavior, traits)
• 3. The variation is inherited
• The outcome of variation is heritable traits that affect survivaland reproduction (evolution)
